1. Field of the Invention
The invention relates to a door handle, e.g. to a doorknob, with a door-side output shaft and a handle facing away from the door leaf, wherein the output shaft and the handle have a common rotation axis and are connected by a preferably electromechanical clutch, so that with an open clutch the handle may be operated, i.e. may be rotated, without entraining the output shaft. With a closed clutch, however, the handle and the output shaft are non-rotatably connected with each other.
2. Description of Relevant Art
In Europe, so-called case locks are generally used in doors, which are also known as mortise locks. Mortise locks are inserted into a recess in the narrow side of the door which is revealed when opening of the door, and are fixed there. These mortise locks have a latch and usually a dead bolt (bolt, for short). At least the latch may usually be retracted by a door handle (mostly in a form of a doorknob) to open the door. In so-called anti-panic locks, also the dead bolt is coupled with the handle, such that also this bolt is retracted upon actuation of the handle. To initiate the rotational movement of the door handle in the mortise lock, the mortise lock has a so-called nut, in which usually a square shaft extending orthogonally to the door leaf is inserted, such that it protrudes at least on one side over the door leaf. The nut is thus some sort of socket for (e.g. form fittingly) receiving the shaft. The door handle is then placed on this free end in a rotationally locked manner.
Locking or unlocking the door is usually done by so-called cylinder locks, which are inserted in the mortise locks. The cylinder locks have a locking cam arranged on a shaft, which cam interacts with the mortise lock. The locking cylinder allows rotation of the locking cam by a user, provided the user is authorized, whereby either a key or a knob serves for actuating the locking cam by the user.
Electromechanical locking systems are based on the electronic identification of a key. The key may be, for example, an active or passive transponder. A lock control exchanges data with the key, thereby checks the authorization of the key, and possibly releases the lock. To release the lock in electromagnetic locking cylinders, the locking cam must be non-rotatably connected (i.e. coupled) with a handle, e.g. a knob. In an unreleased state, at least the handle arranged on the outside of the door is not non-rotatably connected with the locking cam (un-coupled state). For switching between the coupled and the uncoupled locking cam, a clutch (also inter-changeably referred to herein as a switchable clutch) is required. Such clutch, being switchable by the lock control, has on the one hand to be so small that it can be integrated into a locking cylinder, and on the other hand has to absorb comparatively high torques, such that even malfunctioning, e.g. sticking locks can be opened. The energy supply is mostly provided by batteries, which is why the energy requirement of the coupling for a closing and opening operation has to be minimized.
In DE 198 54 454 C2, an electromechanical locking cylinder with an external knob is described, which can be non-rotatably coupled with a locking cam via an electromotively actuated clutch. For this purpose, a shaft is guided from the outside knob into an inner knob, where it carries a support for a linear drive. By means of the linear drive, a coupling element may be inserted in a recess of the hollow shaft which is as well led out from the locking cylinder shaft. The end of the hollow shaft being led out is extended in a flange-like manner and carries the inner knob. The other end of the hollow shaft carries the locking cam.
DE 10 2004 056 989 A1 also describes a locking cylinder with a clutch for a non-rotatable connection of two knobs with a locking cam. The outer knob sits on a pin mounted in the locking cylinder, which pin is non-rotatably connected to a hollow shaft. A coupling gear sits non-rotatably on the hollow shaft. The coupling gear is located in the door-inner-side half of the locking cylinder and is overlapped by axially displaceable coupling claws. The coupling claws each have a radially inwardly facing locking protrusion at their distal end, which can be inserted between the teeth of the coupling gear. Thus, the claws can be non-rotatably coupled to the hollow shaft. When, in addition, the claws engage with counter-claws of a sleeve bearing the locking cam, the lock can be operated by turning the outer knob. The claws are located on an axially displaceable ring and extend from the ring towards the outside of the door. In addition, the ring is permanently non-rotatably connected to a flange bearing the inner knob. By correspondingly displacing the ring, the claws can be disengaged from the counter-claws, whereby the inner knob is decoupled from the locking cam.
U.S. Pat. No. 6,460,903 B1 discloses a door lock with an inner knob and an outer knob acting on a door latch. The inner knob is permanently connected to the door latch via an output shaft, such that said door latch can be permanently retracted by a rotation of the inner knob at any time. The outside knob has a ring being non-rotatably connected to the corresponding handle with a spur toothing in which a coupling ring can be inserted by means of a slider. The coupling ring has two radially placed entraining wing parts, each having two teeth being complementary to the spur toothing. The entraining wing parts are mounted axially displaceable in two slots of a connecting element, such that a rotation of the coupling ring is transmitted to the connecting element. The connecting element has a receiving area in which the output shaft is mounted non-rotatably.
U.S. Pat. No. 6,460,903 B1 also describes an electronic door lock with two knobs that act on a door latch. The inner knob permanently acts on the latch, the outer knob can be indirectly coupled to an output shaft of the inner knob.
In WO 2011/119097 A1, a window handle with locking being adjustable by an electromotor is disclosed. Balls can be inserted by an axial slider in a radial direction in corresponding receiving areas of a rosette screwed to the window, thereby causing the window handle to be locked against rotation.
Alternatively, also clutches are known which are arranged under a cover being arranged directly on the door leaf and serving to connect a doorknob with a nut of a mortise lock (EP 1 662 076 B1, EP 1881135 A1, EP 1522659 B, DE 10 2009 018471 A). These find, however, only limited acceptance for aesthetic reasons.